基于热红外数据的花岗岩铀矿田地表SiO_2含量反演及其铀成矿要素识别

SiO_2 Content Retrieving and Metallogenic Factors Identification of a Granite-Type Uranium Ore-field Based on Thermal Infrared Data

ASTER遥感成像仪发射以来,提供了廉价的多光谱热红外遥感数据,为热红外遥感技术在诸多领域的应用注入了新的活力。本文在分析热红外技术在岩矿领域应用潜力的基础上,将热红外遥感技术应用于花岗岩铀矿找矿中,并以华南某花岗岩铀矿田为例,基于ASTER热红外数据进行了影像镶嵌、辐射定标、大气校正、温度/发射率分离,及其不同波段比值组合模拟的反演算法,对发射率数据进行S iO2含量的定量反演,在反演图上识别出了研究区内明显的硅化断裂带、酸性岩及红层分布信息,识别结果与地质事实相符,并在野外得到了验证。实践表明,热红外遥感技术在花岗岩铀成矿要素提取中效果良好,并将在铀矿找矿工作中发挥积极的指导作用。

Since the sensor of ASTER was launched, low-cost multi-spectral thermal infrared data were available. It injects energy to thermal infrared technology application on many fields. On the basis of analyzing the thermal infrared technology application potential on minerals and rocks, in this paper we apply this technology for extracting of information on granite-type uranium deposits. Taking the granite-type uranium deposits in south china as an example, based on thermal infrared data of ASTER, mosaic, radiometfic calibration, atmospheric correction were made and the temperature and emissivity data were separated from the thermal infrared data. Then, we quantitatively retrieve SiO2 content in the rocks from emissivity data by inversion algorithm simulated from different band ratio combination. According to the inversion map view,we cant extract information of small-scale silicification alteration due to the spatial resolution limitation of ASTER thermal infrared data, but the map clearly shows many large silicified fault zones,the distribution area of acid-rocks and the red beds area that have highest content of the silica. What＇s more, the results conform to the geological facts and they are validated in the field. Above all, the practice proves that information mining technology of thermal infrared data will play an important role in the extraction and analysis of the metallogenic essential factors even in the prospecting target of granite-type uranium deposits.